Boelens



6 1959 E. BOELENS 2,888,255

OPEN-HEARTH FURNACE WITH INCLINED SIDE WALLS Filed March 2, 1953INVENTOR.

[DE/9RD Bantams a/iiwz/ 1M United States Patent OPEN-HEARTH FURNACE WITHINCLINED SIDE WALLS Edgard Boelens, Grivegnee, Belgium, assignor, bymesne assignments, to Socit anonyme Cockerill-Ougree, Seraing, BelgiumApplication March 2, 1953, Serial No. 339,668 Claims priority,application Belgium March 7, 1952 3 Claims. (Cl. 263-46) The presentinvention relates to a furnace which is used in heavy metallurgy andsuch for example, as a furnace for melting, refining, reheating, thermaland other treatments.

It is known that, in certain furnaces, the necessary heat is supplied byhot gases resulting from a combustion or by an effect due to an electriccurrent.

In present-day furnaces of large dimensions, for heavy metallurgy,heated by hot gases resulting from a combustion, the walls are generallyvertical as in reheating furnaces or firing furnaces or inclined towardsthe exterior of the furnace, as for example, in Martin furnaces that isto say that, in known large furnaces the size of the transverse crosssection inside the furnace is constant or runs in a curve in acontinuous manner from the hearth to the arch.

Known furnaces of this type have disadvantages among which may bementioned particularly, the presence of waste spaces at the apex of thepillars near the arch. There exist in these localities turbulent gaseouscurrents which cause local wear in the refractory lining and diminishthe efiiciency of the transmission of heat between the materials to beheated and the hot gases. Furthermore, the components of the arch maypartially melt and fall in droplets on the pillars which they attack itbeing assumed that they are often of a different chemical nature.

The present invention consists in providing in a furnace of a largedimension for heavy metallurgy an arch independently formed of aplurality of elements and overhanging the side walls having internalsurfaces shaped in such a manner that if they are extended theyintersect at a point which is a finite distance above the hearth.

According to an essential feature of the invention, the independent archis composed of a number of elements held in a frame if desired bracedand constituting an assembly independent of the side walls. The internalsurfaces may be flat or curved and they extend in a continuous fashionbetween the hearth and the arch beyond the openings of the workingdoors. In the case where the surfaces are flat, they make, with thehorizontal plane passing at the level of the hearth, an angle whichvaries according to the type of apparatus, the working conditions, etc.The angle of inclination of the surfaces to the horizontal is generallybetween 45 and 85. If the internal surfaces of the lateral walls arecurved, the concavity is directed towards the interior of the apparatus.In some embodiments the opposing curved surfaces have, at points at thesame level, identical radii of curvature, the radii of curvature canalso be different so that it is also possible to give to the lateralwalls and to the independent arch the same radii of curvature.

The present invention will be more easily understood by reference to thefollowing description of the attached drawing which shows purely as anillustration, an embodiment by way of example of the invention.

The figure is a diagrammatic view, in part perspective, of aSiemens-Martin furnace, the front surface being removed.

It will be seen from the figure that a Siemens-Martin furnace comprisesa heanth 2 mounted, for example, on the support beams 2 On the hearthare mounted the lateral walls 3 which, according to the invention, areinclined towards the interior of the furnace that is to say the interiorsurfaces 3 are brought closer together as they approach the arch 4. Thelatter, independent of the inner walls 3, is composed of a plurality ofseparate elements such as bricks, the whole of which is kept together ina frame not shown. On both sides of the arch 4 which overhangs the innerwalls 3, are placed the suspension beams 4 of the said arch and to whichare attached rods such as 4 In one wall 3 are arranged charging doorssuch as 3 in front of which, in the opposite Wall tapholes such as 3 aresituated. It can be seen in the figure that the surfaces 3 are curvedand extend in a continuous manner between the hearth and the arch.

One characteristic of an apparatus constructed according to theinvention resides in the fact that the independent arch, of a pluralityof elements, possesses a surface the projection of which onto ahorizontal plane is less than that of the hearth projected onto the sameplane.

Among the various advantages of a furnace according to the invention mayparticularly be mentioned the very appreciable reduction of the span of:the arch which results in a decrease in weight of the refractory,increased strength and much more rapid and easier repairs.

In addition, in the case where the refractories of the arch and thelateral walls are of different chemical natures capable of giving riseto destructive reactions for one or other of these parts, the structureof a furnace according to the invention prevents the direct contactbetween the fusion products of the refractory components and, as aresult, prevents a chemical reaction between them and the consequentaccelerated deterioration of these linings such as is produced by thesweating of the arch.

Moreover, the most rational section of the furnace produces a betterdistribution of the hot gases of the flame which are driven down towardsthe bath or towards the objects to be heated and the elimination of thewaste spaces which, in the present-day furnaces of straight transversalsection or flared upwardly, favour the upward movement of the hot gases.

Finally for the same hearth surface the refractory linings overhangingthe latter have an external radiating surface less than thecorrespondingly known furnaces; the loss of heat in a furnace formedaccording to the invention will thus be less than in the latter.

What I claim is:

1. An open hearth furnace of the Siemens-Martin type having a hearth,side walls alongside said hearth, an arch overhanging said walls, saidside walls having inwardly inclined surfaces so as to reduce the span ofsaid arch.

2. An open hearth furnace of the Siemens-Martin type having a hearth,side walls alongside said hearth, an arch overhanging said walls, saidside walls having inwardly inclined surfaces so as to reduce the span ofsaid arch, said surfaces being flat and inclined in a continuous mannerbetween said hearth and said arch.

3. An open hearth furnace of the Seimens-Martin type having a hearth,side walls alongside said hearth, an arch overhanging said walls, saidside walls having inwardly inclined surfaces so as to reduce the span ofsaid arch, said surfaces being fiat and inclined in a continuous mannerbetween said hearth and said arch J at an acute angle comprised between45 and 85 with the horizontal plane at the level of said hearth.

References Cited in the file of this patent UNITED STATES PATENTS743,271 Grifiiths Nov. 3, 1903 796,175 Baggaley Aug. 1, 1905 931,945Mehner Aug. 24, 1909 1,286,794 Sahlin Dec. 3, 1918 1,297,149 Greene Mar.11, 1919 41, Tcroutman Mar. 24, 1925 Norton Oct. 9, 1928 Wonning July 1,1930 Moore May 23, 1939 Robertson Apr. 1, 1941 Pollen June 9, 1953FOREIGN PATENTS Australia Oct. 25, 1951 Australia Nov. 26, 1951

